EP 2 055 563 A2, which is incorporated by reference herein, describes a drive system for making available electrical energy for an electric drive train device, wherein a multiplicity of power factors are arranged between an input element, and an output element which is connected to an electrical energy store. In this context, in the described system where different operating parameters are monitored in order to determine a drive torque of the device and to request an increase in electrical power.
EP 1 810 861 A1, which is incorporated by reference herein, is concerned with controlling a power-branched hybrid system. The device described in said document comprises a vehicle drive system comprising: an alternating current traction drive system, a first energy storage system which is electrically coupled to the traction drive by a direct current connection, a second energy storage system which is electrically coupled to the traction drive in such a way that the voltage which is output by the second energy storage system is isolated from the DC connection of a high voltage side. In addition, the device described in said document comprises a low voltage side having a bidirectional step-up converter and an energy management system which is configured to control the first and second energy storage systems if the vehicle is operating in at least one of a precharge mode and a normal operating mode when the traction drive system is activated, wherein the second energy storage system has a super capacitor and a battery with the highest specific energy level, which super capacitor and battery are each coupled to the low voltage side of the step-up converter. In addition, the device described in said document comprises at least one current sensor and one voltage sensor, wherein the energy management system is configured to receive an output signal from the sensor or sensors.